Do people, in general, get what their actions deserve, or is it generally thanks to matters outside their control?

I'd recommend taboo-ing "deserve" to separate ideas of justice from ideas of control and agency. If you replace it with "what their actions influence", the answer is so clearly "both", that I'm confused at how often people struggle with the question.

It's pretty clear that, for any common conception of action and decision, your future experiences are strongly influenced by your actions. It's equally clear that the range of possible future experiences is not infinite, but is limited by your situation.